Pigment and process of making the same.



PAT

T union.

HENRY A. GARDNER, OF "WASHINGTON, DISTRICT OF COLUMBIA.

PIGMENT AND PRGCESS OF MAKING THE SAME.

Application filed March 9,

To (17] whom it may r'onccrn:

Be it known that l, FnNRY A. GARDNER, a citizen of the United States, residing at \v ashington, in the District of Columbia, have invented certain new and useful Improvements in Pigments and Processes of Making the Same, of which the following is a specification.

This intention relatesto certain novel pigments and to processes of making the same, the bject of the invention beingthe production of pigments which contain salts of two or more metals, including lead and barium, which salts are in such a state of intimate association, or possibly even of chemical combination, that they show little or no tendency to segregate or stratify when combined with a paint vehicle or made into paints. This is in marked contradistinction to mixed pigments prepared by grinding the components. The new pigments are prepared by precipitation methods as hereinat'ter fully described.

It is bliOWll that when pigments such as the carbonates. sultates or sulfites of lead, are mixed b v grinding or otherwise with an equimoleeular proportion of an insoluble salt of barium. a:- barium sulfate, a mixed pigment ot deficient hiding power in oil is produced; and moreover. pigments thus prepared show a strong tendency to segregation in presence of the vehicle.

l have found that when pigments containing insoluble compounds of lead and barium are termed simultaneously by a process involving the precipitation of one or both ot the salts from their aqueous solutions the. product is possessed of great hidingpower or opacity, and its components do not exhibit the above-mentioned tendency to stratification: moreover. the, product is decidedly more. resistant to discoloration by hydrogen sullid or the like.

The. invention will be described by certain illustrative examples thercoi", it being understood that itis not restricted to the particular proportions and conditions dolined in the examples.

Example 1: An aqueous solution of a lead salt. such as the normal or basic acetate of lead, is mixed with an aqueous solution of a suitable barium compound, as barium hvdroxid. Equimolecular proportions may be used. To the resulting clear solution there, is added an aqueous solution of a sol uble sullitc, as sodium sulfite, in quantity Specification of Letters Patent.

IPaten'ted Jan. 25, 1916 1915. Seria1N0.13,277.

suliicient to react with and to precipitate the lead and barium as sulfites. Or if desired, I may pass gaseous sulfur dioxid through the clear solution with a like result. In the latter case it is preferred that a basic salt of lead should be used, and the passage of the gas is continued as long as a precipitate continues to form. The pigment thus produced is thoroughly washed with water and dried. It is a white product, and

consists of the insepambl; commingled sulfites of lead and barium.

Example Aqueous solutions of suitable lead and barium compounds are mixed as above described, and the resulting clear solution is precipitated by an aqueous solution of a suitable carbonate. such as normal sodium carbonate, used in sutlicient quantity to precipitate all of the lead and barium as their carbonates. In case basic acetate of lead is used. a like result may be obtained by passing carbon dioxid through the solu tion. so long as a precipitate forms. The precipitate consists in this case of the intimately combined and inseparably commingled mirbonates of lead and barium. The lead carbonates may be either the normal or the basic salt. according to the conditions of the precipitation.

Example Srl o the clear solution containing dissolved compounds of lead and barium, is added an aqueous solution of a sulfate. such as sodium sulfate. so long as a precipitate is formed. The precipitate in this case will consist ot intimately commingled or combined sulfates of lead and barium. ustead o't using a simple precipitant. as described in the foregoing examples. it sometimes desirable t employ a mixture of two or more preeipitants, and thereby to produce a correspondingly complex precipitate.

Example 4: To a clear solutionprcpared by mixing equimolecular DIOPOTtiUilS of suitable soluble compounds of lead and barium, there is added a mixture of sodium carbonate, sodium sultite, and sodium sulfate, these several preeipitauts being in equimolccular proportions, and the total quantity being suliieient for complete precipitation of the lead and barium. The resulting highly eom ple.\' precipitate contains the corresponding insoluble salts both of lead and barium, and treated as above described. Instead of the three precipitants above mentioned, any two of them may be used under conditions I otherwise similar; By varying the, ratio of the lead and barium compounds present in the solution before precipitation, pig

ments may be obtained which contain vacomponent.

proximately equimolecular proportions of the'two salts.- The hiding power; of pigments so prepared is nearly equal to that of rially less tendency'to darken under the fluence of hydrogen sulfid.

Example 5: Lead hydroxid prepared'in any suitable manner, as for example by agipresence of water, is suspended in a solution of bariumhydroxid, the proportion of dissolved barium compound being preferably molecularly' equivalent to the propor tion of suspended lead'compound. The mixture ispthensubjected to a current of carbon dioxid, whereupon a precipitate is formed barium carbonate.

which consists of an extremely intimate mixture of basic carbonate I of lead with It has'been observed in this case that the absorption of the carbon dioxid by the lead is more rapid than when the latter is suspended in water for carbonating, which suggests that the dissolved barium hydroxid mayserve" as a carrier of carbon dioxid to the lead." p p The pigments produced bv any of the foregoing methods may, if desired, be treated by the known physical means to in- I claim e y 1. A precipitate of predetermined composition and suitable for use as a pigment, said precipitate consisting essentially of intivmately commingled carbonates or lead and lead and barium compounds in the desired,

proportions one at least of said compounds being a water-soluble salt, and simulta- 7 neously precipitating the metals from said the pure lead salts, while they have a matemixture in the form of insoluble salts.

3. The hereindescribed method of making tions, which consists 1n preparing a mixture tating minutely subdivided metallic. lead in ing the metals from said mixture in the form of their carbonates. i 4. The hereindescribed method of making pigments containing insoluble carbonates of lead and barium in predetermined proportions, which consists in preparing a mix ture of lead and barium compounds 1n the desired proportions, one at least of said compounds being a water-soluble salt, and reacting on said mixture with carbon dioxid.

5. The herein-described method of making a pigment containing lead and barium carbonates, which consists in forming a basic carbonate of lead and precipitating barium carbonate in intimate association therewith.

In testimon whereof I afiix my signature 1n presence 0 two wltnesses.

HENRY A. GARDNER.

Witnesses 4 N. P. LEoNhRD, C. W. FOWLER. 

